1. Technical Field
The invention relates to electronic equipment. More specifically, the invention relates to a voltage generator, an integrated circuit, and a voltage generating method.
2. Related Art
Semiconductor memory devices are largely divided into volatile memory devices and nonvolatile memory devices.
Volatile memory devices have fast read and write speeds, but lose stored data when power supply is interrupted. Non-volatile memory devices have relatively slow read and write speeds, but maintain stored data even when power supply is interrupted. Accordingly, in order to store data to be maintained irrespective of a state of power supply, a non-volatile memory device is used. Examples of non-volatile memory devices include a read only memory (ROM), a mask ROM (MROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a phase change random access memory (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), and so on. Flash memories are generally divided into a NOR type and a NAND type.
A flash memory has both the advantages of a RAM, that is, free programming and erasure of data, and the advantage of a ROM, that is, preservation of stored data even when power supply is interrupted. Flash memories are widely used as storage media of portable electronic equipment, such as digital cameras, personal digital assistants (PDAs), and MP3 players.
Recently, there has been an increasing demand to improve a degree of integration of a memory.
A semiconductor memory device desirably has a small chip size.